Phenylamides of organoamine polyacetic acids as anti-oxidants in greases



Oct. 26, 1965 5. w. HOTTEN 3,214,377

PHENYLAMIDES OF ORGANOAMINE POLYACETIC ACIDS AS ANTI-XIDANTS IN GREASESFil'ed Aug. 5, 1962 2% AMIDE BASE GREASE AMIDE 1% AMIDE\- OXYGENPRESSURE, PSI

o I I I TIME AT 250F, HOURS INVENTOR BRUCE W. H07'7'EN BY l.- n v.1 a,

United States Patent PHENYLAMIDES 0F dRGANOAMINE POLY- ACETIC. ACIDS ASANTI-OXIDANTS IN GREASES Bruce W. Hotten, Orinda, Califl, assignor toCalifornia Research Corporation, San Francisco, Calif., 21 corporationof Delaware Filed Aug. 3, 1962, Ser. No. 216,015 11 Claims. (Cl.252-33.6)

This application is a continuation-in-part of patent application SerialNo. 58,244, filed September 26, 1960, now abandoned, and patentapplication Serial No. 90,649, filed February 21, 1961, now abandoned.

The present invention pertains to lubricating oil compositionsstabilized against oxidation. In particular, the subject invention isdirected to grease compositions having incorporated therein certainagents which inhibit oxidation of the base grease compositions.

The oxidation of lubricating oil compositions is detrimental to thewearing surfaces being lubricated. This is true not only of freelyflowing lubricating oil compositions but also to thickened lubricatingoil compositions.

Subsequent to their manufacture, grease compositions are stored forrelatively long periods of time prior to their use as a lubricant.During these periods of storage, ordinary grease compositions tend tooxidize, yielding oxidation products which are acidic in nature. Greasecompositions oxidize not only in storage but also during their use inthe lubrication of wearing surfaces, forming products which are acidicin nature. The acidic products which are thus formed are detrimental tothe metal surfaces to which the grease itself is finally applied. Eventhough such grease compositions may initially supply the necessarylubricity for wearing surfaces, such as ball and roller bearings, suchwearing surfaces would be readily corroded due to the corrosive actionof the oxidation products in the greases. Thus although greasecompositions can lubricate bearings and other wearing surfaces, theacidic products attack the metal, causing corrosive damage to thewearing surfaces. Also, sludging caused by oxidation is detrimental tothe proper lubricating of wearing surfaces.

Although the deterioration of lubricating greases by oxidation isusually slow, the partial oxidation products formed in greases catalyzethe oxidation and deterioration of greases until eventually a hard,crusty material which has no lubrication value is formed. Also, suchdeterioration occurs much more rapidly in service than in storage,particularly since the metals such as copper and copperlead alloysfurther catalyze the oxidations of grease compositions.

Modern usage and increasingly severe requirements make it necessary forgrease compositions to have incorporated therein oxidation inhibitorswhich are effective to inhibit oxidation at normal storage temperaturesand also at high service temperatures. Although many oxidationinhibitors such as, for example, tertiary butyl phenol and hydroquinone,are available, they are volatile and evaporate from lubricating oilcompositions at high temperatures.

Oxidation inhibitors useful for grease compositions are described in US.Patents Nos. 2,954,342 and 3,024,277. These inhibitors are alkylamidesof ethylene diamine tetraacetic acid. However, the resulting greasecompositions are not sufficiently inhibited against oxidation towithstand oxidation attacks at extremely high service temperatures andduring conditions wherein the service requirements are severe.

Therefore, it is an object of this invention, to describe greasecompositions having incorporated therein new compounds which areparticularly effective for inhibiting oxidation of grease compositionsat high temperatures.

In accordance with the present invention, it has been discovered thatcertain phenylamides of organoamine polyacetic acids are effective asoxidation inhibitors for grease compositions.

The oxidation inhibitors described herein effectively inhibit oxidationof grease compositions at high temperatures and at low temperatures.

The phenylamides of organoamine polyacetic acids of the subjectinvention have the following generic formula:

o R; CH,-iiN-(OH;) X-

\NRN/ II-I R2 R3 wherein R is an organo radical selected from the groupconsisting of cyclohexane and alkylene radicals containing from 2 to 3carbon atoms; x is a number from 0 to 4; R R and R which may or may notbe alike, are radicals selected from the group consisting of:

wherein x represents the same as that noted hereinabove. In addition, Rmay be selected from the group consisting of CH CH OH and and Thepreferred anti-oxidant described herein is the tetrabenzylamide ofethylene diamine tetraacetic acid of the formula:

0 when], Q 2 2 The phenylamine reactants are exemplified by aniline,benzylamine, phenylethylamine, phenylpropylamine, phenylbutylamine, etc.

The following specific examples illustrate the preparation of theparticular amides which are used in grease compositions to inhibitoxidation thereof.

EXAMPLE I.PREPARATION OF MONOBENZYL- AMIDE OF ETHYILENE DIAMINETETRAACE- T IC ACID A mixture of 292 g. (1 mol) of ethylene diaminetetraacetic acid, 214 g. (2 mols) of benzylamine and 900 ml. xylene washeated with agitation at temperatures of 130 to 140 C. for 16 hours. 27ml. of water was removed by distillation. The xylene was washed out withdiethyl ether. The crude product was agitated with hot dioxan. Therecovered product had a melting point of 181 to 182 C., a neutralizationequivalent of 177, and 9.9% nitrogen (theory= 11.0%

EXAMP-LE II.PREPARATION OF BENZYLAMIDE OF ETHY-LENE DIAMINE TETRAACETICACID A mixture of 292 g. ('1 mol) of ethylene diamine tetraacetic acidand 214 g. (2 mols) of benzylamine was heated with agitation for 2 hoursat a temperature ranging from 160 C. to 200 C. The crude product wasrecrystallized from ethyl alcohol. The alcohol was removed, yielding acrude benzylamide of tetraacetic acid.

EXAIMPLE III.PREPARATION OF DIBENZYLDI- IMIDE OF ETHYLENE DIAMINETETRAACETIC ACID The alcohol-insoluble fraction from Example IIhereinabove was crystallized from dioxan, yielding a pureN,N'-dibenzyldiimide of ethylene diamine tetraacetic acid which had amelting point of 183.5 to 184.5 C, and a nitrogen content of 13.3%(theory= l2.9%).

EXAMPLE IV.PREPARATION OF TETRA-N-BEN- ZYLAMIDE OF ETHYLENE DIAMINETETRA- ACETIC ACID A mixture of 292 g. (1 mol) of ethylene diaminetetraacetic acid and 428 g. (4 mols) of benzylamine was heated withagitation for 3 hours at temperatures ranging from 150 C. to 170 C. Thecrude product was crystallized from dimethyl formamide. The resultingpure tetraamide of ethylene diamine tetraacetic acid had a melting pointof 176.5 C. to l77.0 C. and a nitrogen content of 12.98% (theory:12.95%).

EXAMPLE V.PREPARATION O'F TETRAPHENYL AMIDE OF ETHY'LENE DIAMINETETRAACE- TIC ACID A mixture of 292 g. (1 mol) of ethylene diaminetetraacetic acid and 372 g. (4 mols) of aniline, 253 g. (2.5 mols) oftriethylamine, and 600 ml. of toluene was heated with agitation attemperatures from 45 C. to 80 C. for 1 hour during which time 206 g. ofP01 was added slowly. The reaction mixture was filtered and water-washeduntil free of chlorine, yielding a crude tetraanilide of ethylenediamine tetraacetic acid.

The grease thickening agents which are used in the formation of greasesin which the phenylamides of organoamine polyacetic acids may beincorporated include the organic-type grease thickening agents such asthe conventional soap-type thickeners such as sodium, lithium andcalcium stearates; salts of dibasic acid-diamine condensation products,such as the products of condensing a molar excess of adipic acid withhexamethylene diamine, partially neutralizing the terminal carboxylswith N-decyl amine, then forming the lithium or sodium salt thereof;salts of monoamides of terephthalic acid (e.g., sodium N-octadecylterephthalamate); mixtures of amic acid salts such as lithium hexadecyladiparnate and dibasic acid salts, such as lithium adipamate; ashlessgelling agents, such as pyromellitirnides, etc.

Lubricating oils which can be used as base oils include a wide varietyof lubricating oils, such as naphthenic base, parafiin base, and mixedbase lubricating oils, other hydrocarbon lubricants, e.-g., lubricatingoils derived from coal products, and synthetic oils, e.g., alkylenepolymers (such as polymers of propylene, buty'lene, etc., and themixtures thereof), alkytlene oxide-type polymers (erg. propylene oxidepolymers) and derivatives thereof, including alkylene oxide polymersprepared by polymerizing the alkylene oxides in the presence of water oralcohols, e.g., ethyl alcohol, dicarboxy-lic acid esters (such as thosewhich are prepared by esterifying such dicarboxylic acids as adipicacid, azelaic acid, suberic acid, sebacic acid, alkanol succinic acid,etc., with alcohols such as butyl alcohol, hexyl alcohol, 2-ethyl hexylalcohol, etc.), liquid esters of acids of phosphorus, alkyl benzenes(e.g., monoalkyl benzene such as dodecyl benzene, tetradecyl benzene,etc.), polyphenyls (e.g. biphenyls and terphenyls), alkyl biphenylethers, polymers of silicon (e.g., tetraethyl silicate, tetraisopropylsilicates, hexyl (4-methyl-2-pentoxy) d-isiloxane, poly- (methyl)siloxane, p0ly(methylphenyl) siloxane, etc.). Synthetic oils of thealkylene oxide type polymers which may be used include exemplified bythe alkylene oxide polymers.

The above base oi-ls may be used individually or in combinationsthereof, wherever miscible or wherever made so by the use of mutualsolvents.

The phenyl amides of organoamine polyacetic acids are used herein inlubricating. oil compositions in amounts suflicient to inhibitoxidation; that is, amounts generally between about 0.05% and 10%, byweight. For grease compositions, it is preferred to use from about 2% to10%, by weight, more preferably, 2% to 6%, by weight, based on thefinished grease composition.

Preferably, the oxidation inhibitors of this present invention are usedin high temperature greases, by which is meant greases having droppingpoints not less than about 850 F., and which remain unctuous and do notbecome hard or brittle at 350 F. The oxidation inhibitors describedherein are most advantageously used in high temperature greases and inhigh temperature serv ice because of their low volatility, theirstability, and their marked effectiveness at high temperatures.

The tables set forth herein-below present data showing the effectivenessof the amides described herein as oxidation inhibitors in lubricatingoil compositions.

In grease compositions, unless otherwise noted, the base grease used wasa California base oil thickened with 12% sodium N-octadecylterephthalamate.

The :Thin Film Test measures the ability of the grease composition tomaintain grease like characteristics; particularly, retention ofpliability and resistance to oxidation underexposure of a thin film ofgrease to high temperatures. The test also indicates other greasecharacteristics, such as tendency to bleed, flake, (some greases,although soft and greasy, crack and break), and tendency to becometacky. The Thin Film Test was run as follows. The grease to be testedwas coated on a metal strip. The grease coating was of uniformdimensions: thick, 4;" wide, and 2 /2 long. This grease sample wasplaced in an oven at 350 F. and observed at periodic intervals until thesample no longer existed as a grease. The life of the grease was thenumber of hours during which the grease sample was so heated before itlost its grease-like: characteristics; that is, the time at which thetest sample began to become hard and brittle.

The Bearing Life for a particular grease composition was determined bythe following test procedure, which is known as the Army-Navy High SpeedBearing Test. In this test, a ball bearing packed full of grease W38.operated at i10,000 rpm. continuously for approximately 22 hours at 350F. The apparatus was then cooled to Table l Amine Used for AmidePreparation Grease Characteristics:

Thin Film Life (Hrs) Bomb Oxidation, p.s.i. drop at- 24 Hrs 48 Hrs 100Hrs 200 Hrs 300 Firs 400 Hrs Bearing Life (Hrs.)*

* Geometric Mean of 3 Tests.

(:1) No Amide--Base Grease Alone.

(b) Dibutyl.

(c) Octadecyl.

(d) Aniline.

(e) Benzyl.

Tables 11 and III hereinbelow show the effect on the oxidationresistance of grease compositions using two different batches of thebase grease described hereinabove, containing benzylamide of ethylenediamine tetraacetic acid prepared by varying the mol ratio ofbenzylamide (BZA) to ethylene diamine tetraacetic acid (EDTA) in theamide preparation, forming the mono benzylamide, the di benzylam-ide,the tetrabenzylamide of ethylene diamine tetraacetic acid, etc.

The benzylamide of EDTA was used in the same amounts of 5% by weight.

Table II M01 Ratio BZA to EDTA (a) (b) 2:1 2:1 3+:1

(Amide) (Imide) Grease Characteristics:

Bomb Oxidation, p.s.i. drop at- 100 Hrs- 63+ 11 26 22 18 200 Hrs. 19 3433 23 300 Hrs 27 41 39 26 400 Hrs 30 48 45 30 Bearing Life (Hrs)(Geometric Mean) 43 100 199 18 240 (a) Base Grease Alone. (b) BaseGrease plus 5% Ethylene Diamine Tetraacetic Acid.

Table III M01 Ratio BZA to EDTA (a) 1:1 3:1 3%:1 4:1

Grease Characteristics: Bomb Oxidation, p.s.i. drop at Hrs. 82 18 28 4255 200 Hrs. 34 47 Bearing Life (Hrs) (Geometric Mean) 110 324 535 (a)Base Grease Alone.

Tables IV and V hereinbelow set forth data showing further theeffectiveness of the new additives of this invention as oxidationinhibitors for greases.

Base grease A was a bis(2-ethyl hexyl) sabacate oil thickened with 15%lithium stearate.

Base grease B was a California base mineral oil thick- Table IV GreaseComposition, wt. percent:

1. Base Grease A 2. Base Grease B 51 Amide o Grease Characteristics:

1. Bomb Oxidation (250 F.) (p.s.i. drop at lOOh 65 26 40 2 Bearing Life(300 F 1 can) 74 280 650 550 Table V Grease Composition, wt. percent:

1. Base Grease Grease Characteristics:

1. Bomb Oxidation (250 F.) (p.s.i.

drop at hours) 28 29 82 38 2. Bearing Life (300 F.) (Geometric Mean) 200Table VI hereinbelow presents data showing the effectiveness of the newoxidation inhibitors herein in automatic transmission fluids.

With the exception noted, the lubricating oil compositions were testedaccording to The Federal Specification Test VV-L-791D, Amendment 1,Method 53.8.2. Whereas this method specifies an oil temperature of 300F., the data hereinbelow were obtained at 350 F.

Water-saturated air previously heated to 100 F. was bubbled through 300cc. of the oil to be tested for a period of hours at a rate of 8 litersper hour, using copper and iron wire as catalyst. The temperature of theoil was maintained at 350 F. The viscosity increase of the oil wasnoted.

Oil A was a California base oil containing 0.4% by weight of a zincdialkyl dithiophosphate and 0.4% of a commerically used phenolicantioxidant.

Oil B was the same California base oil containing 0.4% by weight, of azinc dialkyl dithiophosphate and 0.1% of a mixture of triand tetrabenzylamides of ethylene diamine tetraacetic acid.

Table VI Oil A Oil B Viscosity Increase, Percent 40 17 wherein R is anorgano radical selected from the group consisting of cyclohexane andalkylene of from 2 to 3 carbon atoms, R and R are selected from thegroup consisting of CH CO H and and R is selected from the groupconsisting of -CH CO H 6. An oxidation inhibited lubricating oilcomposition comprising a major proportion of an oil of lubricatingviscosity and from 0.05 to weight percent of an amide of an organoaminepolyacetic acid of the formula 1 011,0 ONHOHz and wherein R is an organoradical selected from the group consisting of cyclohexane and alkyleneof from 2 to 3 carbon atoms, R and R are selected from the groupconsisting of CH CO H and and R is selected from the group consisting of8 --CH2CO2H 7. An oxidation inhibited grease composition consistingessentially of grease compositions thickened with an organic type greasethickening agent and containing from 2 to 10 weight percent of an amideof an organo-amine polyacetic acid of the formula NRN 2 a wherein R isan organo radical selected from the group consisting of cyclohexane andalkylene of from 2 to 3 carbon atoms, R and R are selected from thegroup consisting of -CH CO H and -on,ooNHoH,

and R is selected from the group consisting of CH CO H -oH,o oNnom andand

8. A grease composition according to claim 7, wherein said amide istetrabenzylamide of 1,2-cyclohexane dinitrilotetraacetic acid.

9. A grease composition according to claim 7, wherein said amide istribenzylamide of 1,2-cyclohexane dinitrilotetraacetic acid.

10. A grease composition according to claim 7, wherein A said amide ispentabenzylamide of diethylenetrinitn'lopentaacetic acid.

11. A grease composition according to claim 7, wherein said amide istetrabenzylamide of ethylenediamine tetraacetic acid.

References Cited by the Examiner UNITED STATES PATENTS 9/60 Hotten25233.6 3/62 Hotten 252--5l.5

DANIEL E. WYMAN, Primary Examiner.

2. OXIDATION INHIBITED GREASE COMPOSITIONS CONSISTING ESSENTIALLY OF AGREASE COMPOSITION THICKENED WITH AN AMIC ACID SALT AND FROM 2% BYWEIGHT OF TETRABENZYLAMIDE OF ETHYLENE DIAMINE TETRAACETIC ACID.
 7. ANOXIDATION INHIBITED GREASE COMPOSITION CONSISTING ESSENTIALLY OF GREASECOMPOSITION THICKENED WITH AN ORGANIC TYPE GREASE THICKENING AGENT ANDCONTAINING FROM 2 TO 10 WEIGHT PERCENT OF AN AMIDE OF AN ORGANO-AMINEPOLYACETIC ACID OF THE FORMULA